Re: [Qemu-devel] [PATCH 11/35] target/i386: access cpu->interrupt_request with atomics

[Emilio G. Cota]

On Tue, Sep 18, 2018 at 14:04:35 -0700, Richard Henderson wrote:
> On 9/17/18 9:30 AM, Emilio G. Cota wrote:
> >      cpu_reset(cs);
> > -    cs->interrupt_request = sipi;
> > +    atomic_mb_set(&cs->interrupt_request, sipi);
> >      memcpy(&env->start_init_save, &save->start_init_save,
> 
> Why does this need a memory barrier?
>
> Anyway, I think a bare mechanical conversion would be best
> for the first patch and then extra barriers added separately
> and with a description of why.

Almost no corresponding read has a barrier so it's hard to
justify this one. I'll drop it.

Thanks,

                Emilio